--- a/tftp.c
+++ b/tftp.c
@@ -50,7 +50,7 @@ extern	int	segsize;
 #define PKTSIZE    (1432+4) /* SEGSIZE+4 */
 char    ackbuf[PKTSIZE];
 int	timeout;
-jmp_buf	toplevel;
+extern jmp_buf	toplevel;
 jmp_buf	timeoutbuf;
 
 #ifndef OACK
